Apr 8, 2015

MSU publishes Michigan regional fruit reports

Here are Michigan’s regional fruit reports for April 7, courtesy of Michigan State University Extension.

West Michigan

Weather. A bit similar to 2014, spring is slow to arrive in 2015. Fruit growers tend to be pleased with a slow start to spring as it increases the odds of getting through bloom with fewer frost events. Growing degree day (GDD) totals for the general west Michigan area continue to run behind normal by roughly two to three weeks and totals are very similar to this same time in 2014 when first green on apples was April 20. However, if the much warmer weather predicted in the forecast holds true, we will move along quickly in GDD accumulation and could see first green on early apple cultivars in the next few days.

Historically, first green in McIntosh occurs around 125 GDD42. Using forecasted temperatures, that total will be reached by the end of the day Monday, April 13, 2015, which is only a few days behind the average date of April 10.

Slight bud swelling and some silver tip is being reported in apples; sweet cherry and peach buds are swelling slightly, but no green tissue in any tree fruits yet.

Tree fruit diseases. Copper applications on sweet cherries and other stone fruits can be applied at any time. Make sure there is no green tissue showing if you are using full rates to help with bacterial canker. Copper in apples for fire blight management is best timed for delayed dormant or silver tip and it has activity against apple scab as well.

Peach leaf curl sprays should definitely be considered this spring, even if you applied them last fall. If you applied last fall, any residue will be gone due to all the precipitation we’ve had over the winter. If this pattern of a cool, drawn out spring continues, it is perfect environmental conditions for the peach leaf curl fungus to get a foothold in early developing buds.

We are at first bud swell in sweet cherries in the general Grand Rapids, Michigan area. Cool, wet conditions predicted for the next several days could increase bacterial canker populations. As green tissue develops, it becomes susceptible to canker infections if something happens to allow bacteria entry into tissue – this includes frost or freezes and pruning. Avoid pruning sweet cherries in cool, wet conditions predicted for the next several days.

Tree fruit insects. No activity to report for tree fruit insects at this time, but a few of the cool weather moths have been seen flying in the evenings for about a week now. Green fruitworm could start to fly soon. If you have the time, scouting for European red mite overwintering eggs should be done – there could be significant mortality of eggs due to the extra cold winter. Dormant oil sprays will help with San Jose scale, which was significantly higher in some blocks in recent years.

Southwest Michigan

Winter. Winter 2015 was similar to 2014 with extreme cold and snow. Temperatures were below freezing for most of winter and lows were below zero several times. In southwest Michigan, the coldest winter temperatures occurred about Jan. 14 and Feb. 20, according to Michigan State University Enviro-weather.

Low temperatures into the minus teens were common in good fruit sites with good air drainage. Colder temperatures near -20 were common in cold pockets. These cold temperatures caused some winter injury.

Given the extremely cold temperatures during the winter, we expect winter injury to young trees and for the more cold tender fruits similar to 2014. We expect this damage to be more severe in lower, colder sites and away from the moderating effects of Lake Michigan.

Weather. Above freezing low temperatures in March began plant growth in southern Michigan. Most fruit crops have broken dormancy and are at early bud swell. Temperatures rose during the last two weeks, with temperatures rising slowly from lows well below freezing (down to single digits in some locations) to lows around freezing and highs in the 50s and 60s.

This week will be warmer with low temperatures above freezing at night and highs in the 50s and 60s. These temperatures will allow continued plant growth. Rainy weather is forecast for the week and these rains could be infection events for early season diseases. Now is the time to apply dormant treatments to protect crops from overwintering insects and diseases.

Tree fruit. Tree fruit growth is just beginning. Fruit in Berrien County is more advanced than Van Buren County to the north and east. At this stage of development it would require cold temperatures below 20 F to damage the tree fruit flower buds. See “Freeze damage depends on tree fruit stage of development” for more information.

Apricots are at swollen bud. Some buds have burst in Berrien County. Normal apricot bloom in southwest Michigan is about April 15, but it is doubtful we will be warm enough to bloom by then.

Peaches are at swollen bud. At this peach growth stage, rain and temperatures of April 2 may have been sufficient for a peach leaf curl infection. Rain this week can result in further peach leaf curl infections. Peaches are one of the most cold tender tree fruits and flower bud loss is expected when temperatures fall below -10 F. Most injury occurs between -13 and -16 F. Some growers report significant losses and others report they still have more than enough flowers for a good crop.

Sweet cherries and tart cherries are at swollen bud to first green and show little obvious winter injury. Later, as buds swell and burst, damage will become more apparent. Now is the time to apply copper materials to sweet cherries before green tissue is exposed. Sweet cherries are sensitive to copper, so avoid spraying copper when green tissue is exposed. Tart cherries are very tolerant to copper. Copper applications may be helpful in reducing bacterial canker in cherries.

Japanese plums are at white side. European plums are at swollen bud. Some winter injury is expected in Japanese plums, which are less cold hardy than European plums. Little if any damage is expected in European plums, which should show less injury.

Apples of the early blooming variety are at silver tip in Van Buren County. Green tip is visible in early varieties in Berrien County. This means this week’s rains may be apple scab infections. See “An early-season copper application will help avoid feeling the blues about diseases” for more information. We do not expect any winter injury in apples in 2015.

Pears are at early bud swell. Pear psylla are flying.

Small fruit. Grapes have not yet begun growth. There is some winter injury to wine grapes which varies between varieties and different vineyard sites. Many initial assessments early in the winter indicated damage from the cold in January and growers have been warned to delay pruning until after they can carefully assess winter injury.

Blueberry flower buds are swollen. In early varieties, the buds are beginning to burst. Initial assessments indicate some winter injury close to Lake Michigan and more damage away from the lake in cold sites. The damage takes two forms: dark, discolored shoots damaged by extreme cold conditions, and dead flowers in the flower cluster buds.

Leaf buds do not appear swollen, but warmer weather will bring on growth, making them susceptible to mummy berry infections. The recent warm weather should have brought out mummy berry trumpets andgrowers should scout their fields for mummy berries to assess their risk.

Strawberries have greened up and new leaves are emerging from the crown. Over wintering mulches should be removed and raked between the rows.

Brambles are at green tip. Dormant pruning should be completed. In summer-bearing raspberries, last year’s primocanes should be headed (cut back) to the desired height and any remaining floricanes from last year should be removed. Fall-bearing raspberries should be cut or mowed to the ground. Lime sulfurtreatments for anthracnose can be applied.

Southeast Michigan

Winter. We have just experienced the second cold winter in a row. In fact, most of our Michigan State University Enviro-weather stations reported even colder temperatures this winter than last. Many farms and MSU Enviro-weather stations recorded low temperatures this winter in the range of -22 to -28 degrees Fahrenheit, occurring in two distinct windows: one in mid-January and the second in mid- to late February. There was another unusual cold event in early March as well.

We have experienced cold damage to flower buds, twigs and tree trunks on most of our stone fruit crops, pears, summer brambles, blueberries and grapes. Damage to apples has not been detected yet, but more time is needed to determine potential damage. While it is a bit early in the season to make bold crop loss predictions, needless to say we will have some fruit crops with a significant crop reduction or complete loss, and some with longer lasting effects to the woody tissue in the trunks and scaffold branches. More details to follow in this report.

Spring. Cool to cold temperatures have held back development of our fruit crops; most are slightly behind normal. With warmer daytime temperatures the last few days, fruit crops are just beginning to show signs of bud swell and spring growth. Cold nighttime temperatures have kept crop development to a minimum.

With a general lack of rain this spring, our soil moisture conditions are dry across the region. Ground preparation and planting is taking place much earlier than normal. Most growers are completing their winter pruning, brush chopping and removal, and general spring chores in the orchard, as well as just starting to tune-up and calibrate sprayers for the season.

Tree fruits. Apples are at slight bud swell to silver tip for a few varieties. A few more warm days and we will begin to see green tip in Ida Reds and other early leafing varieties. I have not found bud damage in apples. Bud burst will be the time when a more accurate assessment can be made as to possible flower bud damage. Recall that last year there was significant damage to major scaffold branches and trunks that was not anticipated in apples. This damage was most pronounced in Golden Delicious and related strains. This damage did not begin to show up until mid-May or so, and resulted in total tree loss in many blocks. It is too early to assess this type of damage.

Pears show no movement and show some bud damage due to cold temperatures this winter. A more accurate assessment can be made at bud burst when whole blocks rather than individual buds can be assessed. A few pear psylla adults were flying yesterday, April 6.

Peaches are one of the most cold-tender tree fruits and flower bud loss is expected when temperatures fall below -13 F. Most injury occurs between -13 and -16 F. Most growers are experiencing significant flower bud losses, many appearing dehydrated and will be falling off in the next few weeks. It was so cold at many farms that I can see damage to twigs, scaffold branches and even trunks. This damage is showing up as brown- to cinnamon-colored cambium tissue.

Sweet and tart cherries remain dormant to the slightest bud swell and show damage to the fruit buds even on good cherry sites. Tart cherries mostly show less damage in the colder sites than sweets; generally two to three dead florets are being seen in the flower cluster or bud. These levels of damage are greater than damage from a light frost during bloom or a wet, rainy day during pollination at bloom.

Plum damage is extensive in Japanese plums with less in European plums as they are more cold hardy.

Small fruits. Grapes show no movement. There is some damage in Concords and extensive damage to wine grapes varies, however damage varies greatly between varieties and sites.

Strawberry leaves are not emerging from the ground, even at our most southern farms. According toMichigan State University Extension recommendations, it is a bit early to remove mulch.

Raspberry canes of summer fruiting types have a significant amount of cambium browning, indicating potential winter injury. Fall raspberries were mowed a month ago at most farms.

Blueberry buds are starting to show some bud swell. Initial bud assessments indicate damage to flower buds. The damage takes two forms: dead flowers in the flower cluster, or bud and withered shoot tips that dried from cold winds and subfreezing conditions. Generally, what we are seeing is several dead florets per bud.